Theoretical and experimental study on relationship between stress-strain and temperature variation

Abstract

Principle on temperature response to the stress-strain variation is fundamental to the relationship between thermal radiation variation and stress-strain field. Current research indicates that temperature has a sensitive response to rock deformation under the condition of normal temperature background. However, the basic physical relationship between deformation and temperature variation is not clear and need to be investigated further. In this paper, principle on temperature response to stress-strain variation is studied in detail, based on thermodynamics, elastic strain theory, and experiments on both ideal material and rock. In the stage of elastic deformation, results indicate that: 1) temperature increment is positively correlated with volume strain variation. Temperature rises with hydrostatic pressure increase. In other words, temperature rises when the specimen is under the compressive state whereas temperature drops under the tensile state. 2) Pure shear deformation does not contribute to temperature variation. Namely, shape change of specimen does not produce temperature variation. However, there exist the relative tensile area and the compressive one in the specimen under the state of pure shear. Temperature drops within the relative tensile area while temperature rises within the compressive areas during the process of loading. stress-strain, temperature variation, volume strain, pure shear, sine-wave loadRecently, more and more thermal anomalies corresponding to earthquake and fault activity are investigated by using satellite remote sensing technology although many problems remain unsolved. Up to now, almost thermal infrared seismic precursors are found by rethinking of some phenomena, maybe related to seismic activity, after earthquake occurred. And it is lack of necessary analyses to physical mechanism on thermal infrared anomaly prior to earthquake, so that it does not judge the facticity and reliability of seismic precursor [1] . Relationship between thermal field and strain field during the process of fault deformation is the physical basis for applying the satellite infrared information or land surface temperature to analyze earthquake or fault activity. The temperature variation on rock deformation during the process of loading is studied through a series of experiments [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] , which lays the foundation for further work, but these experimental results are not in accordance with one another, some of which are conflicted with the classical physical principle. For instance, some researchers suppose that relationship between temperature variation and stress state is related with rock category, which temperature rises in some rocks, keeps stable in some rocks, and drops in some rocks, under compression state.There are two major reasons for the aforementioned discordant experimental results: 1) limitation of the experimental technology. The temperature variation during the deformation of rock is minimal. Therefore, the valid temperature signal...

Energy analysis for damage and catastrophic failure of rocks

“…Some consistent conclusions are made: Rock fracturing is generally accompanied by strong acoustic emission; the strain increase is accompanied by decreasing infrared radiation intensity, electromagnetic radiation intensity and temperature after fracturing; before rock fracturing under compression, acoustic emission signal is weak while the infrared radiation intensity, electromagnetic radiation intensity and temperature would rise [1][2][3][4][5][6][7][8][9][10][11][12]. Some experimental studies [17] have shown that the change of material temperature or infrared radiation intensity is related to the volumetric strain. When the volumetric strain be-comes smaller, the temperature or infrared radiation intensity usually increases.…”

“…  e c a q mK (17) By applying the Mises energy-based yield criterion characterized by compressive strength: The underground tunnel shown in Figure 13 is in the critical failure state under the geo-stress q e listed in Table 4. If a positive stress increment ∆q is adopted in the surrounding geo-mass, the damage in the inner tunnel wall will further develop radially to the position with a radius of r s (see Figure 13).…”

“…Only with complete understanding of these problems, it is possible to make correct stability evaluation for underground structures. Some valuable studies have been made in these aspects by our research group and other colleagues [17][18][19][20][21][22][23][24][25][26][27].…”

An Experimental Study on Evolution of the Thermal Field of En Echelon Faults During the Meta‐Instability Stage

“…Our laboratory established a system of temperature observation in order to study the relationship between heat and strain [23] , which can use both the contact temperature measurement system and the infrared thermal imaging system at the same time to observe temperature changes under different deformation conditions and in different parts of the samples. Two aspects of the work have been carried out using this experimental system: Firstly, under the adiabatic condition, for the reversible process (elastic deformation), the temperature of rocks of thermal expansion material (thermal stress coefficient is positive) rises when loading and drops when unloading by compression, and for adiabatic irreversible processes (plastic deformation, damage and friction), the temperature of the rock rises [14,24] . That is to say, there are two mechanisms of temperature rise, one is caused by strain, and the other is due to friction.…”

A thermal physical index to explore current tectonic activity with satellite remote sensing

“…The temperature rises when the specimen is in a compressive state whereas the temperature drops when it is in a tensile state. This is to say, it is possible to judge whether a fault is active or not by detecting temperature change in a typical tectonic zone on the basis of the mentioned-above relationship between stress-strain and temperature variation [2][3][4][5]. However, information of tectonic activity under the surface and exterior factors, such as solar radiation, need be considered when using land surface temperature to judge current fault activity.…”